Flasher switches



May 22, 1956 c. T. BLUME 2,747

FLASHER swncnss Filed Oct. 10, 1952 2 Sheets-Sheet 1 INSULATION INSULATION 7/ 1 I INSULATION /NVENTO/2 CARL T BLUME ATTORNEY y 2, 1956 c. T. BLUME 2,747,052

FLASHER SWITCHES Filed Oct. 10, 1952 2 Sheets-Sheet 2 5 lNvENTOl? CAI/2L T BLUME ATTORNEY United States Patent FLASHER SWITCHES Carl T. Blume, West Newton, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application October 10, 1952, Serial No. 314,129

3 Claims. (Cl. 200-113) This invention relates to automatic electric switches and more specifically to devices for the periodic opening and closing of electric circuits.

There are many applications that require a relatively slow periodic opening and closing of electric circuits, such as flashing and blinking devices for traHic signals, display signs, and so forth. Such devices require regular periodic openings and closings with the period ranging from one tenth of a second to several seconds.

Accordingly, it is one of the objects of this invention to provide an inexpensive and readily manufactured automatic periodically operating switch which will regularly open and close a circuit.

When a device of this type has operated continuously for any extended period of time, the total number of openings and closings becomes very large, and the Wear on the contact points of the switch becomes a limiting factor on the useful life of the device. It is, therefore, necessary to incorporate in the design for such a device means for minimizing the deterioration of these contact points, such as providing for a sharp make and break and the provision of a sliding or wiping action.

Another object is, therefore, to make an automatic switch of the type described which has a snap or sudden action for ra id making and breaking contact, and also a certain wiping action between the contact points.

Other and further objects and advantages of this invention will become apparent as the description thereof progresses, reference being had to the accompanying drawings, wherein:

Fig. l is a view of one form of complete switch;

Fig. 2 is a partial side View of this same switch;

Fig. 3 is a diagrammatic representation of electrical connections that may be used in connection with this invention;

Fig. 4 is a detail view of the action of the spring as described in Figs. 1 and 2; and

Fig. 5 is a detail view of the contact points as described in Figs. 1 and 2.

deferring to Figs. 1 and 2 of the drawing, the switch comprises a suitable insulating base 1 on which is mounted leaf springs 2, 3 and 4, bracket 5 and stop 6. As will be seen from Fig. l, where leaf spring 4 is shown broken away, springs 2 and 3 are formed from a single piece and are thus electrically interconnected. However, it should be noted that springs 2 and 3, bracket 5, spring 4 and stop 6 are all insulated one from the other along their respective base sections by a suitable insulating material positioned therebetween. Spring 2 is maintained in a slightly bent position by resistance wire 7, which is fastened to the upper part of spring 2 and to bracket 5, and connected electrically to spring 4 by means of resistance wire 8. Spring 3, carrying contact point 9, is mounted on base 1 in substantially the same plane as spring 2, and under the edge of the projecting portion of spring 2. A U-shaped wire spring 11 is hooked over the top edge of spring 3 and the bottom edge of the ice projecting portion of spring 2. Spring 4, carrying contact point 10, is mounted on base 1 substantially parallel to and a short distance from spring 3, positioned so that a slight bending of spring 3 will cause contacts 9 and 10 to come together.

Referring now to Fig. 3, the electrical connections are as follows. A suitable source of current 12 is connected to spring 4 and through resistance wire 8 to stretched resistance wire 7, thence through springs 2, 11, and 3 to some load device 13, the other terminal of which is connected to the second terminal of current source 12 through switch 14.

When switch 14 is closed, a current flows through the circuit as described above, heating resistance wire 7, which is thereby caused to expand. This expansion of resistance wire 7 allows the top of spring 2 to move to the right (as shown in Fig. 3). When spring 2 passes the dead center position of U-shaped spring 11, the latter causes spring 3 to snap to the left, closing contact points 9 and 10. This closure of points 9 and 10 short circuits resistance wires 7 and 8, and allows the full voltage of current source 12 to be applied to load 13.

As soon as the resistance wires 7 and 8 are short circuited by the closing of contacts 9 and 10, as described above, the current passing through these wires drops to a very small value. This causes wire 7 to cool and contract, pulling the top of spring 2 to the left. When spring 2 passes dead center of U-shaped spring 11, the latter causes spring 3 to snap to the right, quickly separating contact points 9 and 10. The device is now in its original position, and ready for another cycle.

it can be seen that this device will alternately open and close contacts 9 and 10, thereby periodically allowing full current flow to the load.

The action of U-shaped spring 11 is shown by Fig. 4. Referring to the drawing, sketch a shows the relative position of springs 22., 11, and 3 at the beginning of a cycle. As the top of spring 2 moves toward the right, it approaches dead center (as shown in sketch b), compressing spring 11. As spring 2 passes dead center the energy stored in compressed spring 11 is suddenly released, causing spring 3 to be quickly snapped to the left (as shown in sketch c) with considerable force, thus closing contacts 9 and 10 very quickly, with a minimum of sparking. The same action takes place in reverse when the contacts are opened.

This snap action of the contacts under the influence of spring 11 results in another desirable efiect, as shown in an exaggerated manner by Fig. 5. Referring to the drawing, sketch (1 shows springs 3 and 4 an instant after spring 3 and contact 9, traveling with considerable speed in the direction indicated by the arrow, have struck spring 4 and contact 10. The momentum of spring 3 and contact 9 will cause spring 4 to bend slightly to the left; then, upon recovery, both springs will bend slightly to the right (as shown by sketch e), finally coming to rest in equilibrium position as shown by sketch This slight bending back and forth produces a sliding or wiping action between contacts 9 and 10 which tends to remove any accumulated oxides or dirt, keeping the contact surfaces clean and bright.

The rate of heating of wire 7 will depend on the amount of current flowing through it, which current is determined primarily by the size of the load 13. The larger the load, the faster will be such heating and the resultant frequency of operation of the device. However, with any given load the cyclic rate of the present device may be adjusted by varying numerous factors. The resistance of wires 7 and 8, the angle of wire 7, the angle and the stiffness of spring 11 all can be adjusted as desired. Increasing the angle or resistance of Wire 7 will increase the speed of the cycle, while decreasing the resistance or increasing the diameter of wire 7 will decrease the cyclic rate. The relative duration of the periods during which contacts 9 and 10 are open or closed can be controlled by varying the angles of springs 2, 3 and. 11. By these means it has been found possible to achieve cyclic rates ranging from less than one cycle per second to as much as twenty or more cycles per second.

This invention has a number of advantages over prior devices used in the art. It is simple in design, positive in action, and can be cheaply and easily made by standard manufacturing methods. However, in spite of this, it is very durable because of the quick opening and closing characteristic and the wiping action of the contacts.

This invention is not limited to the particular details or" construction, materials and processes described, as many equivalentswilltsuggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. A self-cycling, rapid-action make-and-break circuit comprising a base member, a first leaf spring mounted on said base member said first leaf spring including two arms, one of said arms having a contact point thereon, asecond leaf spring adjacent to said first spring said second spring also having a contact point thereon, a bracket mounted on said base member, a tensioned heat-expansible resistance element attached to said bracket and to one of said arms, and spring means cooperating with the arms of said first leaf spring and responsive to relaxation of said tensioned element to move one of said contact points into engagement with the other, thereby substantially reducing current fiow through said tensioned element, said means being thereafter responsive to, the subsequent tightening of said tensioned element, as a result of such current flow reduction, to move said one contact point out of engagement with the other, thereby substantially increasing current flow through, said tensioned element to relax its tension sufficiently to cause repetition of the make-and break switching cycle.

2. A self-cycling rapid-action make-and-break device comprising a base member, a first leaf spring mounted on said base member, said; first leaf spring comprising a T-shaped arm and a substantially rectangularlyshaped arni positioned under a projecting portion of said T-shaped arm, said rectangularly-shaped arm having a contact point thereon, a second leaf spring adjacentto said first spring, said second spring also having a contact point thereon, a bracket mounted on said base member, a tensioned heat-expansible resistance element attached to said bracket and to said T-shaped arm, and

means interengaging said T-shaped arm and said rectangularly-shaped arm, said means being responsive to relaxation of said tensioned, element to snap one of said contact points into engagement with the other thereby substantially reducing current flow through said tensioned element, said means being thereafter responsive to the subsequent tightening ofsaid tensioned element, as a result of such current flow reduction, to move said one contact point out of engagement with the other, thereby substantially increasingcurrent fiow through said tensioncd element to relax its tension sufficiently to cause repetition of the make-and-break switching cycle.

3. A self-cycling rapid' action make-and-break device comprising a base member, a first leaf spring mounted on said base member, said first leaf spring comprising a T-shaped arm and a substantially rectangularly-shaped arm positioned under a projecting portion of said T-shaped arm, said rectangularly-shaped arm having a contact point thereon, a second leaf spring adjacent to and facing said rectangularly-shaped arm of said first spring, said second spring also having a. contact point thereon, a bracket mounted on said base member, a tensioned heat-expansible resistance element attached to said bracket and, to said T-shaped, arm, and a substantially I l-shaped spring having one end hooked under a bottom edge of said T-shaped arm and its other end hooked over the top edge of said rectangularly-shaped arm, said U-shaped spring being responsive to relaxation of said tensioned. element due tov current flow therethrough whereby said contact points are snapped into engagement and current flow through said resistance element is substantiallyreduced, said U-shaped spring being thereafter responsive to. the subsequent tightening of said tensioned element, as a result of such current flow reduction, to snap said contact points out of engagement, thereby substantially increasing current flow through said tensioned element torelax itstension sutficiently. to cause repetition of the make-and-break switching cycle.

References Cited in, the file of this patent UNITED STATES PATENTS 1,959,205. Hanel May 15, 1934 2,074,345 Schmidinger Mar. 23, 1937 2,133,309 Schmidinger Oct. 18, 1938 2,184,699 Horton Dec. 26, 1939 2,299,767 Schmidinger Oct. 27, 1942 2,302,399 Stimson Nov. 17, 1942 2,308,522 Leuthold Jan. 19, 1943 2,312,974 Owens Mar. 2, 1943 2,321,049 Schmidinger June 8, 1943 2,508,637 Bolesky May 23, 1950 2,558,219 Kohl June 26, 1951 2,672,563 Boddy Mar. 16, 1954 2,699,161 Pees Jan. 11, 1955 

